> import qualified Char

> words' :: String -> [String]
> words' [] = []
> words' (x:xs)
>  | Char.isSpace x  =  words1 xs
>  | otherwise       =  case words' xs of
>                         []  ->  [[x]]
>                         (ys:yss) -> (x:ys):yss
>  where
>   words1 [] = []
>   words1 xs@(y:ys) | Char.isSpace y  =  words1 ys
>                    | otherwise       =  [] : words' xs

> main = interact (unwords . words')